The present invention comprises a new and distinct variety of Ribes nidigrolaria known by the varietal name Jostaki.
The new variety was discovered in 1980 in a selective breeding program in the Federal Republic of Germany. The breeding took place in Koln-Vogelsang and the selection at Breitbrunn, Federal Republic of Germany. The new variety is an F3 open pollinated selection of Black currant--Variety "Schwarze Traube".times.Gooseberry--wild variety Ribes divaricatum. The botanical denomination used for the new species "Ribes nidigrolaria" is a neologism the creation of which is not yet officially known.
Ribes nidigrolaria are new amphidiploid species hybrids between black current (Ribes nigrum) and gooseberry (Ribes grossularia).
The new variety has been repeatedly asexually reproduced in the Federal Republic of Germany. It has been found to retain its distinctive characteristics through successive propagation.
Since 1948, crosses followed by polyploidization have been made between cultivars and wild species of black currant and gooseberry, to combine useful plant and resistance characteristics and high quality of berries. Selections have yielded amphidiploid breeding lines with desired combination or resistance to leaf fall diseases (Pseudopeziza ribes and Cronartium ribicola), mildew (Sphaerotheca mors uvae) with freedom from gall mites ("big bud").
Selfings of primary amphidiploids showed the expected complex heredity of growth and resistance characteristics. The fertility of F2-hybrids, however, was low.
By crossing induced tetraploid F1-hybrids of different origins, the effect of inbreeding depression was overcome. It was possible to obtain F2-hybrids with large fruits, high yielding capacity and sufficient self-fertility. Of those with the desired resistance combination, selection for future cultivars was started.
In 1977 the first cultivar of Ribes nidigrolaria was introduced under the name of Josta.